I used to have the 2500 for about 2 years and loved it. I never completely warmed up to the curved links of the bracelet ,though, which was it's only aesthetic flaw, in my opinion. Once I saw the photos leaking out of the 8500, I had to have it. I went from the 2500 XL with white arabics to the 8500 XL with orange arabics. A week later I traded it in for the 42mm version. Even though it's the same watch, there are a few differences between the 2 sizes. The XL version has a slightly more domed crystal, a beveled date opening, and a slightly darker bezel. In dim lighting it turned completely black whereas the 42mm version always stays gray. Those features are all better but I wanted a smaller watch.
The bracelet on the 8500 is much nicer because the center links are flat but the older style clasp was better looking.
Both the new and old version are very versatile and look great on the bracelet, rubber strap, and NATO.
Even though the price is higher on the 8500, you're getting getting a beautiful in-house movement with a longer power reserve, a display back, a ceramic bezel versus an aluminum one, raised applied arabics and raised omega writing under the omega symbol, a beautiful blue lume, and a nicer bracelet. The 8500 doesn't have a quick set date though. It works like a GMT watch instead. In the 2nd crown position, as the crown is turned, instead of the date advancing, the hour hand jumps in 1 hour increments, which is great for traveling between different timezone, but is a little tedious when changing the date more than a couple of days. One good feature is that the date can be advanced both forward and backwards.
Compared to other brands, $4600, the price new ones are selling for, is a relative bargain. The SubC sells for $2500 to $3000 more.
Here are some more photos.
The crystal disappears at certain angles, just like Breitlings.
Here's the 2500.
The 2500 was a bit thinner
